The objective of the proposed research is to explain the relatively poor mortality experience of older males in the United States as compared with males and females in other industrialized countries, and with U.S. females. In accomplshing this objectve it is necessary to account for international differences in mortality rates over age 45 among males, among females, and among the ratios of male to female mortality in industrialized countries. The overall approach relies, first, on comparative time-series analyses of the effects of economic development and fluctuations in male and female mortality rates over age 45 for each of 25 industrialized countries during 1920-1976. These countries are located in Western Europe, North America, and Australasia. Additional analyses then attempt to interpret the findings on the differential impact among the industrialized countries of broad economic changes on mortality trends of older males and females. These multivariate analyses examine the extent to which factors cited in the literatures on aging, social demography, and psychological stress explain th differential impact of economic development on mortality trends for the older population. In this study, controls are used for the contributory effects of environmental and biological influences by including such influences in the general multivariate models of total and cause-specific mortality. The principal variables which are hypothesized to explain differential international mortality rates by sex among the older populations are: income, employment status - especially retirement and unemployment, occupation, educational attainment, marital status, including widowhood and family composition, parity of women, ethnic heterogeneity, institutionalization and other isolation of the older populations, and availability of health care.